Material Specifications
Quartzite, Granite & Limestone Boulder Retaining Walls
The stone you choose decides how much a wall weighs, how tightly it locks together, and how it weathers through Wasatch winters. Here's how we select and size boulders for engineered walls across Salt Lake, Davis, Utah, Weber, Summit, and Wasatch counties.
- Angular quarried stone that interlocks lift to lift
- Base boulders sized to the wall height and soil
- Color-matched to existing landscapes and HOA/ACC rules
Boulder Wall Cost Estimator
Utah permit & PE stamp required. Measured from the bottom of the footing, this wall exceeds 4 feet, so stamped engineering, geogrid design, and a permit are required. We coordinate all three.
Ballpark installed range
$13,200 – $22,800
Includes keyed-in base, filter fabric, drain-rock chimney & SDR-35 toe drain. Final price set after a site visit.
Why Stone Selection Is a Structural Decision
A boulder retaining wall is a gravity wall. There's no concrete footing or steel holding it up — the wall resists the soil behind it with its own mass, its batter into the hillside, and the friction between stones. That makes the boulders themselves the structural material, and their properties matter as much as how they look.
Three properties drive our selection. Density: more weight per boulder means more resistance to sliding and overturning. Shape: angular, blocky stones with flat faces bear on each other and interlock, while round river rock rolls. Durability: stone with low water absorption resists the freeze-thaw cracking and spalling that Utah winters inflict on softer rock.
Utah Boulder Types Compared
| Stone | Typical density | Shape & stacking | Freeze-thaw durability | Best use |
|---|---|---|---|---|
| Quartzite | ~160–170 lb/ft³ | Angular, blocky fracture faces; excellent interlock | Excellent — very hard, low absorption | Structural base and face courses; tall and engineered walls |
| Granite | ~160–170 lb/ft³ | Sub-angular to blocky; heavy and uniform | Excellent | Base courses, high-load walls, canyon and bench lots |
| Basalt | ~175–185 lb/ft³ | Angular and blocky; very dense | Excellent | Compact high-mass walls; dark modern accents |
| Limestone | ~145–170 lb/ft³ | Flat bedding planes that stack tightly | Good to very good — select dense, unfractured pieces | Ledged, formal walls; garden and terrace walls |
| Sandstone | ~135–155 lb/ft³ | Flat, ledge-like slabs | Fair to good — softer and more absorbent | Accent and lower walls; native red palettes required by mountain ACCs |
| Moss rock / fieldstone | Varies by parent rock | Rounded to sub-angular, weathered face | Varies | Natural low-profile walls and upper courses |
Why We Build With Utah Quartzite
Quartzite is sandstone that has been recrystallized under heat and pressure until its quartz grains fuse together. The result is one of the hardest, least absorbent building stones available — around 7 on the Mohs hardness scale. Large quartzite formations run through the Wasatch and Oquirrh ranges, which is why tan, gold, and gray quartzite is the most common structural boulder on the Wasatch Front.
For retaining walls, quartzite's real advantage is how it breaks. Quarried quartzite fractures into angular, blocky shapes with flat faces, so each boulder sits on the stones below with broad contact instead of balancing on points. That interlock, combined with an 8-to-12 degree batter, is what keeps a gravity wall from rotating forward when the soil behind it gets wet.
Granite is the other workhorse. It's similarly dense and durable, often a little rounder in shape, and comes in grays and speckled tones that suit canyon-mouth neighborhoods. On many walls we use the heaviest, blockiest pieces of either stone for the base course and choose upper courses for fit and color.
How Boulders Are Sized
Boulders are graded by the trade's "man" classes — a naming convention, not a crew size. Every boulder we set is placed with an excavator and thumb, not by hand.
| Class | Approx. size | Approx. weight | Typical role |
|---|---|---|---|
| One-man | 12–18 in | 50–200 lb | Chinking and caps on low walls |
| Two-man | 18–24 in | 200–700 lb | Upper courses of low walls |
| Three-man | 24–36 in | 700–2,000 lb | Face courses on 3–5 ft walls |
| Four-man | 36–48 in | 2,000–4,000 lb | Base courses on 4–6 ft walls |
| Five-man | 48–54 in | 4,000–6,000 lb | Base courses on tall, engineered walls |
| Six-man | 54–60 in | 6,000–8,000 lb | Base of the tallest walls |
The base course always carries the largest stones in the wall. Each course above steps back and generally uses smaller boulders, so the wall narrows toward the top and keeps its center of gravity tucked into the hillside. On walls over 4 feet, the engineer's design specifies minimum boulder sizes per course alongside the geogrid layout.
Color, Texture & Matching Your Landscape
Tan & gold quartzite
Warm, sun-bleached tones that suit most Wasatch bench homes and blend with native scrub oak and grasses.
Gray granite
Speckled gray and salt-and-pepper tones common near the Cottonwood canyons; pairs well with modern architecture.
Red sandstone
The Heber Valley palette. Mountain architectural control committees often require native red stone to match the surrounding terrain.
Moss rock
Lichen-covered, weathered faces for wooded and alpine lots where a wall should look like it has always been there.
Many HOAs and Architectural Review Boards (ARBs) require native-stone matching, from Promontory, The Colony at White Pine Canyon, and Deer Crest in the Park City area to Pepperwood in Sandy, Three Falls in Alpine, and Wolf Creek Ranch. We source stone to match existing walls and submit samples for approval before delivery.
What Goes Behind the Boulders
How we engineer walls over 4 feetFrequently Asked Questions
Is quartzite or granite better for a retaining wall?
Both are excellent structural stones: dense, hard, and highly resistant to freeze-thaw damage. Quarried quartzite tends to break into more angular, blocky shapes that interlock tightly, while granite is similarly heavy and often slightly rounder. The right choice usually comes down to color, availability, and how well individual pieces fit — and many walls use the blockiest pieces of either stone in the base course.
How much do retaining wall boulders weigh?
It depends on size class and stone density. As a rough guide, a two-man boulder (18–24 inches) weighs 200–700 lb, a three-man (24–36 inches) 700–2,000 lb, and a four-man (36–48 inches) 2,000–4,000 lb. Base boulders on tall walls can exceed 6,000 lb, which is why all placement is done with an excavator and why access to your yard affects cost.
Can I use rounded river rock or rocks from my yard for a retaining wall?
Not for a structural wall. Rounded stones lack flat bearing faces, so they roll and shift rather than locking together, and they can't be battered back into a slope securely. River rock works well for low decorative borders and dry creek beds, but anything holding back soil should be built from angular quarried stone.
Does sandstone hold up in Utah winters?
Sandstone is softer and more absorbent than quartzite or granite, so water that soaks in can freeze and spall the surface. Dense, sound pieces perform well when the wall is properly drained. We hand-select sandstone for load-bearing courses, keep it out of standing water, and where a native red palette is required we may use denser stone in the base and sandstone on the visible face.
How many tons of boulders does a retaining wall need?
As a rough guide, a 4-foot boulder wall uses somewhere around half a ton to a ton of stone per linear foot, and taller walls need considerably more because base boulders grow with wall height. Stone density and how tightly pieces fit also matter. We calculate tonnage during the site visit so stone delivery matches the design.
Related Retaining Wall Services
- Engineered Retaining Walls Over 4 Feet Stamped PE engineering, geogrid reinforcement, and permit coordination for tall and surcharged retaining walls.
- Failing Retaining Wall Repair & Replacement Tear-out and rebuild of rotting railroad tie, leaning block, and slumping rock walls with proper drainage.
- Sloped Backyard Terracing & Excavation Tiered boulder walls, hillside cut-and-fill, and access creation to turn steep slopes into usable yard.
Cities We Serve
See local soil conditions, permit rules, preferred stone, and typical project costs for your city.
Salt Lake County
- Boulder retaining walls in Draper
- Boulder retaining walls in Cottonwood Heights
- Boulder retaining walls in Holladay
- Boulder retaining walls in Sandy
- Boulder retaining walls in Millcreek
- Boulder retaining walls in Salt Lake City
- Boulder retaining walls in Herriman
- Boulder retaining walls in South Jordan
- Boulder retaining walls in Bluffdale
- Boulder retaining walls in Riverton
- Boulder retaining walls in West Jordan
- Boulder retaining walls in Midvale
- Boulder retaining walls in Murray